Scientific Constants

Scientific constants are built into scipy, so writing by hand is unnecessary.

By the end of this file you should have seen simple examples of:

  1. How to access the built-in constants in scipy

Further reading:
https://docs.scipy.org/doc/scipy/reference/constants.html


In [1]:
# Python imports
import scipy.constants

In [2]:
# Use the scipy 'constants' object to get various constants
print("The standard acceleration of gravity is: {0} m/s^2" \
      .format(scipy.constants.g) )
print("Speed of light is: {0} m/s" \
      .format(scipy.constants.speed_of_light) )

print("Avogadros Number is: {0} units/mole" \
      .format(scipy.constants.Avogadro) )
print("Planck's Constant is: {0} m^2 kg/s" \
      .format(scipy.constants.h) )
print("The Boltzmann constant is: {0} m^2 kg s^-2 K^-1" \
      .format(scipy.constants.k) )

print("The elementary charge is: {0} C".format(scipy.constants.e) )


The standard acceleration of gravity is: 9.80665 m/s^2
Speed of light is: 299792458.0 m/s
Avogadros Number is: 6.022140857e+23 units/mole
Planck's Constant is: 6.62607004e-34 m^2 kg/s
The Boltzmann constant is: 1.38064852e-23 m^2 kg s^-2 K^-1
The elementary charge is: 1.6021766208e-19 C

In [3]:
# Python's import statement makes it possible import directly:
from scipy.constants import g, h, k

print("The standard acceleration of gravity is: {0} m/s^2".format(g))
print("Planck's Constant is: {0} m^2 kg/s".format(h))
print("The Boltzmann constant is: {0} m^2 kg s^-2 K^-1".format(k))


The standard acceleration of gravity is: 9.80665 m/s^2
Planck's Constant is: 6.62607004e-34 m^2 kg/s
The Boltzmann constant is: 1.38064852e-23 m^2 kg s^-2 K^-1

In [4]:
# SciPy constants also contain the 2014 CODATA recommended values 
g = scipy.constants.physical_constants['Newtonian constant of gravitation']
print("The newtonian constant of gravitation is: {0} {1}" \
      .format(g[0], g[1]))

electron_mass = scipy.constants.physical_constants['electron mass']
print("The mass of an electron is: {0} {1}" \
      .format(electron_mass[0], electron_mass[1]))

proton_mass = scipy.constants.physical_constants['proton mass']
print("The mass of a proton is: {0} {1}" \
      .format(proton_mass[0], proton_mass[1]))

neutron_mass = scipy.constants.physical_constants['neutron mass']
print("The mass of a neutron is: {0} {1}"\
      .format(neutron_mass[0], neutron_mass[1]))


The newtonian constant of gravitation is: 6.67408e-11 m^3 kg^-1 s^-2
The mass of an electron is: 9.10938356e-31 kg
The mass of a proton is: 1.672621898e-27 kg
The mass of a neutron is: 1.674927471e-27 kg

A more complete list of constants is available via help:


In [5]:
help(scipy.constants)


Help on package scipy.constants in scipy:

NAME
    scipy.constants

DESCRIPTION
    ==================================
    Constants (:mod:`scipy.constants`)
    ==================================
    
    .. currentmodule:: scipy.constants
    
    Physical and mathematical constants and units.
    
    
    Mathematical constants
    ======================
    
    ================  =================================================================
    ``pi``            Pi
    ``golden``        Golden ratio
    ``golden_ratio``  Golden ratio
    ================  =================================================================
    
    
    Physical constants
    ==================
    
    ===========================  =================================================================
    ``c``                        speed of light in vacuum
    ``speed_of_light``           speed of light in vacuum
    ``mu_0``                     the magnetic constant :math:`\mu_0`
    ``epsilon_0``                the electric constant (vacuum permittivity), :math:`\epsilon_0`
    ``h``                        the Planck constant :math:`h`
    ``Planck``                   the Planck constant :math:`h`
    ``hbar``                     :math:`\hbar = h/(2\pi)`
    ``G``                        Newtonian constant of gravitation
    ``gravitational_constant``   Newtonian constant of gravitation
    ``g``                        standard acceleration of gravity
    ``e``                        elementary charge
    ``elementary_charge``        elementary charge
    ``R``                        molar gas constant
    ``gas_constant``             molar gas constant
    ``alpha``                    fine-structure constant
    ``fine_structure``           fine-structure constant
    ``N_A``                      Avogadro constant
    ``Avogadro``                 Avogadro constant
    ``k``                        Boltzmann constant
    ``Boltzmann``                Boltzmann constant
    ``sigma``                    Stefan-Boltzmann constant :math:`\sigma`
    ``Stefan_Boltzmann``         Stefan-Boltzmann constant :math:`\sigma`
    ``Wien``                     Wien displacement law constant
    ``Rydberg``                  Rydberg constant
    ``m_e``                      electron mass
    ``electron_mass``            electron mass
    ``m_p``                      proton mass
    ``proton_mass``              proton mass
    ``m_n``                      neutron mass
    ``neutron_mass``             neutron mass
    ===========================  =================================================================
    
    
    Constants database
    ------------------
    
    In addition to the above variables, :mod:`scipy.constants` also contains the
    2014 CODATA recommended values [CODATA2014]_ database containing more physical
    constants.
    
    .. autosummary::
       :toctree: generated/
    
       value      -- Value in physical_constants indexed by key
       unit       -- Unit in physical_constants indexed by key
       precision  -- Relative precision in physical_constants indexed by key
       find       -- Return list of physical_constant keys with a given string
       ConstantWarning -- Constant sought not in newest CODATA data set
    
    .. data:: physical_constants
    
       Dictionary of physical constants, of the format
       ``physical_constants[name] = (value, unit, uncertainty)``.
    
    Available constants:
    
    ======================================================================  ====
    ``alpha particle mass``                                                 6.64465723e-27 kg
    ``alpha particle mass energy equivalent``                               5.971920097e-10 J
    ``alpha particle mass energy equivalent in MeV``                        3727.379378 MeV
    ``alpha particle mass in u``                                            4.001506179127 u
    ``alpha particle molar mass``                                           0.004001506179127 kg mol^-1
    ``alpha particle-electron mass ratio``                                  7294.29954136 
    ``alpha particle-proton mass ratio``                                    3.97259968907 
    ``Angstrom star``                                                       1.00001495e-10 m
    ``atomic mass constant``                                                1.66053904e-27 kg
    ``atomic mass constant energy equivalent``                              1.492418062e-10 J
    ``atomic mass constant energy equivalent in MeV``                       931.4940954 MeV
    ``atomic mass unit-electron volt relationship``                         931494095.4 eV
    ``atomic mass unit-hartree relationship``                               34231776.902 E_h
    ``atomic mass unit-hertz relationship``                                 2.2523427206e+23 Hz
    ``atomic mass unit-inverse meter relationship``                         751300661660000.0 m^-1
    ``atomic mass unit-joule relationship``                                 1.492418062e-10 J
    ``atomic mass unit-kelvin relationship``                                10809543800000.0 K
    ``atomic mass unit-kilogram relationship``                              1.66053904e-27 kg
    ``atomic unit of 1st hyperpolarizability``                              3.206361329e-53 C^3 m^3 J^-2
    ``atomic unit of 2nd hyperpolarizability``                              6.235380085e-65 C^4 m^4 J^-3
    ``atomic unit of action``                                               1.0545718e-34 J s
    ``atomic unit of charge``                                               1.6021766208e-19 C
    ``atomic unit of charge density``                                       1081202377000.0 C m^-3
    ``atomic unit of current``                                              0.006623618183 A
    ``atomic unit of electric dipole mom.``                                 8.478353552e-30 C m
    ``atomic unit of electric field``                                       514220670700.0 V m^-1
    ``atomic unit of electric field gradient``                              9.717362356e+21 V m^-2
    ``atomic unit of electric polarizability``                              1.6487772731e-41 C^2 m^2 J^-1
    ``atomic unit of electric potential``                                   27.21138602 V
    ``atomic unit of electric quadrupole mom.``                             4.486551484e-40 C m^2
    ``atomic unit of energy``                                               4.35974465e-18 J
    ``atomic unit of force``                                                8.23872336e-08 N
    ``atomic unit of length``                                               5.2917721067e-11 m
    ``atomic unit of mag. dipole mom.``                                     1.854801999e-23 J T^-1
    ``atomic unit of mag. flux density``                                    235051.755 T
    ``atomic unit of magnetizability``                                      7.8910365886e-29 J T^-2
    ``atomic unit of mass``                                                 9.10938356e-31 kg
    ``atomic unit of mom.um``                                               1.992851882e-24 kg m s^-1
    ``atomic unit of permittivity``                                         1.1126500560536183e-10 F m^-1
    ``atomic unit of time``                                                 2.418884326509e-17 s
    ``atomic unit of velocity``                                             2187691.26277 m s^-1
    ``Avogadro constant``                                                   6.022140857e+23 mol^-1
    ``Bohr magneton``                                                       9.274009994e-24 J T^-1
    ``Bohr magneton in eV/T``                                               5.7883818012e-05 eV T^-1
    ``Bohr magneton in Hz/T``                                               13996245042.0 Hz T^-1
    ``Bohr magneton in inverse meters per tesla``                           46.68644814 m^-1 T^-1
    ``Bohr magneton in K/T``                                                0.67171405 K T^-1
    ``Bohr radius``                                                         5.2917721067e-11 m
    ``Boltzmann constant``                                                  1.38064852e-23 J K^-1
    ``Boltzmann constant in eV/K``                                          8.6173303e-05 eV K^-1
    ``Boltzmann constant in Hz/K``                                          20836612000.0 Hz K^-1
    ``Boltzmann constant in inverse meters per kelvin``                     69.503457 m^-1 K^-1
    ``characteristic impedance of vacuum``                                  376.73031346177066 ohm
    ``classical electron radius``                                           2.8179403227e-15 m
    ``Compton wavelength``                                                  2.4263102367e-12 m
    ``Compton wavelength over 2 pi``                                        3.8615926764e-13 m
    ``conductance quantum``                                                 7.748091731e-05 S
    ``conventional value of Josephson constant``                            483597900000000.0 Hz V^-1
    ``conventional value of von Klitzing constant``                         25812.807 ohm
    ``Cu x unit``                                                           1.00207697e-13 m
    ``deuteron g factor``                                                   0.8574382311 
    ``deuteron mag. mom.``                                                  4.33073504e-27 J T^-1
    ``deuteron mag. mom. to Bohr magneton ratio``                           0.0004669754554 
    ``deuteron mag. mom. to nuclear magneton ratio``                        0.8574382311 
    ``deuteron mass``                                                       3.343583719e-27 kg
    ``deuteron mass energy equivalent``                                     3.005063183e-10 J
    ``deuteron mass energy equivalent in MeV``                              1875.612928 MeV
    ``deuteron mass in u``                                                  2.013553212745 u
    ``deuteron molar mass``                                                 0.002013553212745 kg mol^-1
    ``deuteron rms charge radius``                                          2.1413e-15 m
    ``deuteron-electron mag. mom. ratio``                                   -0.0004664345535 
    ``deuteron-electron mass ratio``                                        3670.48296785 
    ``deuteron-neutron mag. mom. ratio``                                    -0.44820652 
    ``deuteron-proton mag. mom. ratio``                                     0.3070122077 
    ``deuteron-proton mass ratio``                                          1.99900750087 
    ``electric constant``                                                   8.854187817620389e-12 F m^-1
    ``electron charge to mass quotient``                                    -175882002400.0 C kg^-1
    ``electron g factor``                                                   -2.00231930436182 
    ``electron gyromag. ratio``                                             176085964400.0 s^-1 T^-1
    ``electron gyromag. ratio over 2 pi``                                   28024.95164 MHz T^-1
    ``electron mag. mom.``                                                  -9.28476462e-24 J T^-1
    ``electron mag. mom. anomaly``                                          0.00115965218091 
    ``electron mag. mom. to Bohr magneton ratio``                           -1.00115965218091 
    ``electron mag. mom. to nuclear magneton ratio``                        -1838.28197234 
    ``electron mass``                                                       9.10938356e-31 kg
    ``electron mass energy equivalent``                                     8.18710565e-14 J
    ``electron mass energy equivalent in MeV``                              0.5109989461 MeV
    ``electron mass in u``                                                  0.00054857990907 u
    ``electron molar mass``                                                 5.4857990907e-07 kg mol^-1
    ``electron to alpha particle mass ratio``                               0.0001370933554798 
    ``electron to shielded helion mag. mom. ratio``                         864.058257 
    ``electron to shielded proton mag. mom. ratio``                         -658.2275971 
    ``electron volt``                                                       1.6021766208e-19 J
    ``electron volt-atomic mass unit relationship``                         1.0735441105e-09 u
    ``electron volt-hartree relationship``                                  0.03674932248 E_h
    ``electron volt-hertz relationship``                                    241798926200000.0 Hz
    ``electron volt-inverse meter relationship``                            806554.4005 m^-1
    ``electron volt-joule relationship``                                    1.6021766208e-19 J
    ``electron volt-kelvin relationship``                                   11604.5221 K
    ``electron volt-kilogram relationship``                                 1.782661907e-36 kg
    ``electron-deuteron mag. mom. ratio``                                   -2143.923499 
    ``electron-deuteron mass ratio``                                        0.0002724437107484 
    ``electron-helion mass ratio``                                          0.0001819543074854 
    ``electron-muon mag. mom. ratio``                                       206.766988 
    ``electron-muon mass ratio``                                            0.0048363317 
    ``electron-neutron mag. mom. ratio``                                    960.9205 
    ``electron-neutron mass ratio``                                         0.00054386734428 
    ``electron-proton mag. mom. ratio``                                     -658.2106866 
    ``electron-proton mass ratio``                                          0.000544617021352 
    ``electron-tau mass ratio``                                             0.000287592 
    ``electron-triton mass ratio``                                          0.0001819200062203 
    ``elementary charge``                                                   1.6021766208e-19 C
    ``elementary charge over h``                                            241798926200000.0 A J^-1
    ``Faraday constant``                                                    96485.33289 C mol^-1
    ``Faraday constant for conventional electric current``                  96485.3251 C_90 mol^-1
    ``Fermi coupling constant``                                             1.1663787e-05 GeV^-2
    ``fine-structure constant``                                             0.0072973525664 
    ``first radiation constant``                                            3.74177179e-16 W m^2
    ``first radiation constant for spectral radiance``                      1.191042953e-16 W m^2 sr^-1
    ``Hartree energy``                                                      4.35974465e-18 J
    ``Hartree energy in eV``                                                27.21138602 eV
    ``hartree-atomic mass unit relationship``                               2.9212623197e-08 u
    ``hartree-electron volt relationship``                                  27.21138602 eV
    ``hartree-hertz relationship``                                          6579683920711000.0 Hz
    ``hartree-inverse meter relationship``                                  21947463.13702 m^-1
    ``hartree-joule relationship``                                          4.35974465e-18 J
    ``hartree-kelvin relationship``                                         315775.13 K
    ``hartree-kilogram relationship``                                       4.850870129e-35 kg
    ``helion g factor``                                                     -4.255250616 
    ``helion mag. mom.``                                                    -1.074617522e-26 J T^-1
    ``helion mag. mom. to Bohr magneton ratio``                             -0.001158740958 
    ``helion mag. mom. to nuclear magneton ratio``                          -2.127625308 
    ``helion mass``                                                         5.0064127e-27 kg
    ``helion mass energy equivalent``                                       4.499539341e-10 J
    ``helion mass energy equivalent in MeV``                                2808.391586 MeV
    ``helion mass in u``                                                    3.01493224673 u
    ``helion molar mass``                                                   0.00301493224673 kg mol^-1
    ``helion-electron mass ratio``                                          5495.88527922 
    ``helion-proton mass ratio``                                            2.99315267046 
    ``hertz-atomic mass unit relationship``                                 4.4398216616e-24 u
    ``hertz-electron volt relationship``                                    4.135667662e-15 eV
    ``hertz-hartree relationship``                                          1.5198298460088e-16 E_h
    ``hertz-inverse meter relationship``                                    3.3356409519815204e-09 m^-1
    ``hertz-joule relationship``                                            6.62607004e-34 J
    ``hertz-kelvin relationship``                                           4.7992447e-11 K
    ``hertz-kilogram relationship``                                         7.372497201e-51 kg
    ``inverse fine-structure constant``                                     137.035999139 
    ``inverse meter-atomic mass unit relationship``                         1.331025049e-15 u
    ``inverse meter-electron volt relationship``                            1.2398419739e-06 eV
    ``inverse meter-hartree relationship``                                  4.556335252767e-08 E_h
    ``inverse meter-hertz relationship``                                    299792458.0 Hz
    ``inverse meter-joule relationship``                                    1.986445824e-25 J
    ``inverse meter-kelvin relationship``                                   0.0143877736 K
    ``inverse meter-kilogram relationship``                                 2.210219057e-42 kg
    ``inverse of conductance quantum``                                      12906.4037278 ohm
    ``Josephson constant``                                                  483597852500000.0 Hz V^-1
    ``joule-atomic mass unit relationship``                                 6700535363.0 u
    ``joule-electron volt relationship``                                    6.241509126e+18 eV
    ``joule-hartree relationship``                                          2.293712317e+17 E_h
    ``joule-hertz relationship``                                            1.509190205e+33 Hz
    ``joule-inverse meter relationship``                                    5.034116651e+24 m^-1
    ``joule-kelvin relationship``                                           7.2429731e+22 K
    ``joule-kilogram relationship``                                         1.1126500560536185e-17 kg
    ``kelvin-atomic mass unit relationship``                                9.2510842e-14 u
    ``kelvin-electron volt relationship``                                   8.6173303e-05 eV
    ``kelvin-hartree relationship``                                         3.1668105e-06 E_h
    ``kelvin-hertz relationship``                                           20836612000.0 Hz
    ``kelvin-inverse meter relationship``                                   69.503457 m^-1
    ``kelvin-joule relationship``                                           1.38064852e-23 J
    ``kelvin-kilogram relationship``                                        1.53617865e-40 kg
    ``kilogram-atomic mass unit relationship``                              6.022140857e+26 u
    ``kilogram-electron volt relationship``                                 5.60958865e+35 eV
    ``kilogram-hartree relationship``                                       2.061485823e+34 E_h
    ``kilogram-hertz relationship``                                         1.356392512e+50 Hz
    ``kilogram-inverse meter relationship``                                 4.524438411e+41 m^-1
    ``kilogram-joule relationship``                                         8.987551787368176e+16 J
    ``kilogram-kelvin relationship``                                        6.5096595e+39 K
    ``lattice parameter of silicon``                                        5.431020504e-10 m
    ``Loschmidt constant (273.15 K, 100 kPa)``                              2.6516467e+25 m^-3
    ``Loschmidt constant (273.15 K, 101.325 kPa)``                          2.6867811e+25 m^-3
    ``mag. constant``                                                       1.2566370614359173e-06 N A^-2
    ``mag. flux quantum``                                                   2.067833831e-15 Wb
    ``Mo x unit``                                                           1.00209952e-13 m
    ``molar gas constant``                                                  8.3144598 J mol^-1 K^-1
    ``molar mass constant``                                                 0.001 kg mol^-1
    ``molar mass of carbon-12``                                             0.012 kg mol^-1
    ``molar Planck constant``                                               3.990312711e-10 J s mol^-1
    ``molar Planck constant times c``                                       0.119626565582 J m mol^-1
    ``molar volume of ideal gas (273.15 K, 100 kPa)``                       0.022710947 m^3 mol^-1
    ``molar volume of ideal gas (273.15 K, 101.325 kPa)``                   0.022413962 m^3 mol^-1
    ``molar volume of silicon``                                             1.205883214e-05 m^3 mol^-1
    ``muon Compton wavelength``                                             1.173444111e-14 m
    ``muon Compton wavelength over 2 pi``                                   1.867594308e-15 m
    ``muon g factor``                                                       -2.0023318418 
    ``muon mag. mom.``                                                      -4.49044826e-26 J T^-1
    ``muon mag. mom. anomaly``                                              0.00116592089 
    ``muon mag. mom. to Bohr magneton ratio``                               -0.00484197048 
    ``muon mag. mom. to nuclear magneton ratio``                            -8.89059705 
    ``muon mass``                                                           1.883531594e-28 kg
    ``muon mass energy equivalent``                                         1.692833774e-11 J
    ``muon mass energy equivalent in MeV``                                  105.6583745 MeV
    ``muon mass in u``                                                      0.1134289257 u
    ``muon molar mass``                                                     0.0001134289257 kg mol^-1
    ``muon-electron mass ratio``                                            206.7682826 
    ``muon-neutron mass ratio``                                             0.1124545167 
    ``muon-proton mag. mom. ratio``                                         -3.183345142 
    ``muon-proton mass ratio``                                              0.1126095262 
    ``muon-tau mass ratio``                                                 0.0594649 
    ``natural unit of action``                                              1.0545718e-34 J s
    ``natural unit of action in eV s``                                      6.582119514e-16 eV s
    ``natural unit of energy``                                              8.18710565e-14 J
    ``natural unit of energy in MeV``                                       0.5109989461 MeV
    ``natural unit of length``                                              3.8615926764e-13 m
    ``natural unit of mass``                                                9.10938356e-31 kg
    ``natural unit of mom.um``                                              2.730924488e-22 kg m s^-1
    ``natural unit of mom.um in MeV/c``                                     0.5109989461 MeV/c
    ``natural unit of time``                                                1.28808866712e-21 s
    ``natural unit of velocity``                                            299792458.0 m s^-1
    ``neutron Compton wavelength``                                          1.31959090481e-15 m
    ``neutron Compton wavelength over 2 pi``                                2.1001941536e-16 m
    ``neutron g factor``                                                    -3.82608545 
    ``neutron gyromag. ratio``                                              183247172.0 s^-1 T^-1
    ``neutron gyromag. ratio over 2 pi``                                    29.1646933 MHz T^-1
    ``neutron mag. mom.``                                                   -9.662365e-27 J T^-1
    ``neutron mag. mom. to Bohr magneton ratio``                            -0.00104187563 
    ``neutron mag. mom. to nuclear magneton ratio``                         -1.91304273 
    ``neutron mass``                                                        1.674927471e-27 kg
    ``neutron mass energy equivalent``                                      1.505349739e-10 J
    ``neutron mass energy equivalent in MeV``                               939.5654133 MeV
    ``neutron mass in u``                                                   1.00866491588 u
    ``neutron molar mass``                                                  0.00100866491588 kg mol^-1
    ``neutron to shielded proton mag. mom. ratio``                          -0.68499694 
    ``neutron-electron mag. mom. ratio``                                    0.00104066882 
    ``neutron-electron mass ratio``                                         1838.68366158 
    ``neutron-muon mass ratio``                                             8.89248408 
    ``neutron-proton mag. mom. ratio``                                      -0.68497934 
    ``neutron-proton mass difference``                                      2.30557377e-30 
    ``neutron-proton mass difference energy equivalent``                    2.07214637e-13 
    ``neutron-proton mass difference energy equivalent in MeV``             1.29333205 
    ``neutron-proton mass difference in u``                                 0.001388449 
    ``neutron-proton mass ratio``                                           1.00137841898 
    ``neutron-tau mass ratio``                                              0.52879 
    ``Newtonian constant of gravitation``                                   6.67408e-11 m^3 kg^-1 s^-2
    ``Newtonian constant of gravitation over h-bar c``                      6.70861e-39 (GeV/c^2)^-2
    ``nuclear magneton``                                                    5.050783699e-27 J T^-1
    ``nuclear magneton in eV/T``                                            3.152451255e-08 eV T^-1
    ``nuclear magneton in inverse meters per tesla``                        0.02542623432 m^-1 T^-1
    ``nuclear magneton in K/T``                                             0.0003658269 K T^-1
    ``nuclear magneton in MHz/T``                                           7.622593285 MHz T^-1
    ``Planck constant``                                                     6.62607004e-34 J s
    ``Planck constant in eV s``                                             4.135667662e-15 eV s
    ``Planck constant over 2 pi``                                           1.0545718e-34 J s
    ``Planck constant over 2 pi in eV s``                                   6.582119514e-16 eV s
    ``Planck constant over 2 pi times c in MeV fm``                         197.3269788 MeV fm
    ``Planck length``                                                       1.616229e-35 m
    ``Planck mass``                                                         2.17647e-08 kg
    ``Planck mass energy equivalent in GeV``                                1.22091e+19 GeV
    ``Planck temperature``                                                  1.416808e+32 K
    ``Planck time``                                                         5.39116e-44 s
    ``proton charge to mass quotient``                                      95788332.26 C kg^-1
    ``proton Compton wavelength``                                           1.32140985396e-15 m
    ``proton Compton wavelength over 2 pi``                                 2.10308910109e-16 m
    ``proton g factor``                                                     5.585694702 
    ``proton gyromag. ratio``                                               267522190.0 s^-1 T^-1
    ``proton gyromag. ratio over 2 pi``                                     42.57747892 MHz T^-1
    ``proton mag. mom.``                                                    1.4106067873e-26 J T^-1
    ``proton mag. mom. to Bohr magneton ratio``                             0.0015210322053 
    ``proton mag. mom. to nuclear magneton ratio``                          2.7928473508 
    ``proton mag. shielding correction``                                    2.5691e-05 
    ``proton mass``                                                         1.672621898e-27 kg
    ``proton mass energy equivalent``                                       1.503277593e-10 J
    ``proton mass energy equivalent in MeV``                                938.2720813 MeV
    ``proton mass in u``                                                    1.007276466879 u
    ``proton molar mass``                                                   0.001007276466879 kg mol^-1
    ``proton rms charge radius``                                            8.751e-16 m
    ``proton-electron mass ratio``                                          1836.15267389 
    ``proton-muon mass ratio``                                              8.88024338 
    ``proton-neutron mag. mom. ratio``                                      -1.45989805 
    ``proton-neutron mass ratio``                                           0.99862347844 
    ``proton-tau mass ratio``                                               0.528063 
    ``quantum of circulation``                                              0.00036369475486 m^2 s^-1
    ``quantum of circulation times 2``                                      0.00072738950972 m^2 s^-1
    ``Rydberg constant``                                                    10973731.568508 m^-1
    ``Rydberg constant times c in Hz``                                      3289841960355000.0 Hz
    ``Rydberg constant times hc in eV``                                     13.605693009 eV
    ``Rydberg constant times hc in J``                                      2.179872325e-18 J
    ``Sackur-Tetrode constant (1 K, 100 kPa)``                              -1.1517084 
    ``Sackur-Tetrode constant (1 K, 101.325 kPa)``                          -1.1648714 
    ``second radiation constant``                                           0.0143877736 m K
    ``shielded helion gyromag. ratio``                                      203789458.5 s^-1 T^-1
    ``shielded helion gyromag. ratio over 2 pi``                            32.43409966 MHz T^-1
    ``shielded helion mag. mom.``                                           -1.07455308e-26 J T^-1
    ``shielded helion mag. mom. to Bohr magneton ratio``                    -0.001158671471 
    ``shielded helion mag. mom. to nuclear magneton ratio``                 -2.12749772 
    ``shielded helion to proton mag. mom. ratio``                           -0.7617665603 
    ``shielded helion to shielded proton mag. mom. ratio``                  -0.7617861313 
    ``shielded proton gyromag. ratio``                                      267515317.1 s^-1 T^-1
    ``shielded proton gyromag. ratio over 2 pi``                            42.57638507 MHz T^-1
    ``shielded proton mag. mom.``                                           1.410570547e-26 J T^-1
    ``shielded proton mag. mom. to Bohr magneton ratio``                    0.001520993128 
    ``shielded proton mag. mom. to nuclear magneton ratio``                 2.7927756 
    ``speed of light in vacuum``                                            299792458.0 m s^-1
    ``standard acceleration of gravity``                                    9.80665 m s^-2
    ``standard atmosphere``                                                 101325.0 Pa
    ``standard-state pressure``                                             100000.0 Pa
    ``Stefan-Boltzmann constant``                                           5.670367e-08 W m^-2 K^-4
    ``tau Compton wavelength``                                              6.97787e-16 m
    ``tau Compton wavelength over 2 pi``                                    1.11056e-16 m
    ``tau mass``                                                            3.16747e-27 kg
    ``tau mass energy equivalent``                                          2.84678e-10 J
    ``tau mass energy equivalent in MeV``                                   1776.82 MeV
    ``tau mass in u``                                                       1.90749 u
    ``tau molar mass``                                                      0.00190749 kg mol^-1
    ``tau-electron mass ratio``                                             3477.15 
    ``tau-muon mass ratio``                                                 16.8167 
    ``tau-neutron mass ratio``                                              1.89111 
    ``tau-proton mass ratio``                                               1.89372 
    ``Thomson cross section``                                               6.6524587158e-29 m^2
    ``triton g factor``                                                     5.95792492 
    ``triton mag. mom.``                                                    1.504609503e-26 J T^-1
    ``triton mag. mom. to Bohr magneton ratio``                             0.0016223936616 
    ``triton mag. mom. to nuclear magneton ratio``                          2.97896246 
    ``triton mass``                                                         5.007356665e-27 kg
    ``triton mass energy equivalent``                                       4.500387735e-10 J
    ``triton mass energy equivalent in MeV``                                2808.921112 MeV
    ``triton mass in u``                                                    3.01550071632 u
    ``triton molar mass``                                                   0.00301550071632 kg mol^-1
    ``triton-electron mass ratio``                                          5496.92153588 
    ``triton-proton mass ratio``                                            2.99371703348 
    ``unified atomic mass unit``                                            1.66053904e-27 kg
    ``von Klitzing constant``                                               25812.8074555 ohm
    ``weak mixing angle``                                                   0.2223 
    ``Wien frequency displacement law constant``                            58789238000.0 Hz K^-1
    ``Wien wavelength displacement law constant``                           0.0028977729 m K
    ``{220} lattice spacing of silicon``                                    1.920155714e-10 m
    ======================================================================  ====
    
    
    Units
    =====
    
    SI prefixes
    -----------
    
    ============  =================================================================
    ``yotta``     :math:`10^{24}`
    ``zetta``     :math:`10^{21}`
    ``exa``       :math:`10^{18}`
    ``peta``      :math:`10^{15}`
    ``tera``      :math:`10^{12}`
    ``giga``      :math:`10^{9}`
    ``mega``      :math:`10^{6}`
    ``kilo``      :math:`10^{3}`
    ``hecto``     :math:`10^{2}`
    ``deka``      :math:`10^{1}`
    ``deci``      :math:`10^{-1}`
    ``centi``     :math:`10^{-2}`
    ``milli``     :math:`10^{-3}`
    ``micro``     :math:`10^{-6}`
    ``nano``      :math:`10^{-9}`
    ``pico``      :math:`10^{-12}`
    ``femto``     :math:`10^{-15}`
    ``atto``      :math:`10^{-18}`
    ``zepto``     :math:`10^{-21}`
    ============  =================================================================
    
    Binary prefixes
    ---------------
    
    ============  =================================================================
    ``kibi``      :math:`2^{10}`
    ``mebi``      :math:`2^{20}`
    ``gibi``      :math:`2^{30}`
    ``tebi``      :math:`2^{40}`
    ``pebi``      :math:`2^{50}`
    ``exbi``      :math:`2^{60}`
    ``zebi``      :math:`2^{70}`
    ``yobi``      :math:`2^{80}`
    ============  =================================================================
    
    Weight
    ------
    
    =================  ============================================================
    ``gram``           :math:`10^{-3}` kg
    ``metric_ton``     :math:`10^{3}` kg
    ``grain``          one grain in kg
    ``lb``             one pound (avoirdupous) in kg
    ``pound``          one pound (avoirdupous) in kg
    ``oz``             one ounce in kg
    ``ounce``          one ounce in kg
    ``stone``          one stone in kg
    ``grain``          one grain in kg
    ``long_ton``       one long ton in kg
    ``short_ton``      one short ton in kg
    ``troy_ounce``     one Troy ounce in kg
    ``troy_pound``     one Troy pound in kg
    ``carat``          one carat in kg
    ``m_u``            atomic mass constant (in kg)
    ``u``              atomic mass constant (in kg)
    ``atomic_mass``    atomic mass constant (in kg)
    =================  ============================================================
    
    Angle
    -----
    
    =================  ============================================================
    ``degree``         degree in radians
    ``arcmin``         arc minute in radians
    ``arcminute``      arc minute in radians
    ``arcsec``         arc second in radians
    ``arcsecond``      arc second in radians
    =================  ============================================================
    
    
    Time
    ----
    
    =================  ============================================================
    ``minute``         one minute in seconds
    ``hour``           one hour in seconds
    ``day``            one day in seconds
    ``week``           one week in seconds
    ``year``           one year (365 days) in seconds
    ``Julian_year``    one Julian year (365.25 days) in seconds
    =================  ============================================================
    
    
    Length
    ------
    
    =====================  ============================================================
    ``inch``               one inch in meters
    ``foot``               one foot in meters
    ``yard``               one yard in meters
    ``mile``               one mile in meters
    ``mil``                one mil in meters
    ``pt``                 one point in meters
    ``point``              one point in meters
    ``survey_foot``        one survey foot in meters
    ``survey_mile``        one survey mile in meters
    ``nautical_mile``      one nautical mile in meters
    ``fermi``              one Fermi in meters
    ``angstrom``           one Angstrom in meters
    ``micron``             one micron in meters
    ``au``                 one astronomical unit in meters
    ``astronomical_unit``  one astronomical unit in meters
    ``light_year``         one light year in meters
    ``parsec``             one parsec in meters
    =====================  ============================================================
    
    Pressure
    --------
    
    =================  ============================================================
    ``atm``            standard atmosphere in pascals
    ``atmosphere``     standard atmosphere in pascals
    ``bar``            one bar in pascals
    ``torr``           one torr (mmHg) in pascals
    ``mmHg``           one torr (mmHg) in pascals
    ``psi``            one psi in pascals
    =================  ============================================================
    
    Area
    ----
    
    =================  ============================================================
    ``hectare``        one hectare in square meters
    ``acre``           one acre in square meters
    =================  ============================================================
    
    
    Volume
    ------
    
    ===================    ========================================================
    ``liter``              one liter in cubic meters
    ``litre``              one liter in cubic meters
    ``gallon``             one gallon (US) in cubic meters
    ``gallon_US``          one gallon (US) in cubic meters
    ``gallon_imp``         one gallon (UK) in cubic meters
    ``fluid_ounce``        one fluid ounce (US) in cubic meters
    ``fluid_ounce_US``     one fluid ounce (US) in cubic meters
    ``fluid_ounce_imp``    one fluid ounce (UK) in cubic meters
    ``bbl``                one barrel in cubic meters
    ``barrel``             one barrel in cubic meters
    ===================    ========================================================
    
    Speed
    -----
    
    ==================    ==========================================================
    ``kmh``               kilometers per hour in meters per second
    ``mph``               miles per hour in meters per second
    ``mach``              one Mach (approx., at 15 C, 1 atm) in meters per second
    ``speed_of_sound``    one Mach (approx., at 15 C, 1 atm) in meters per second
    ``knot``              one knot in meters per second
    ==================    ==========================================================
    
    
    Temperature
    -----------
    
    =====================  =======================================================
    ``zero_Celsius``       zero of Celsius scale in Kelvin
    ``degree_Fahrenheit``  one Fahrenheit (only differences) in Kelvins
    =====================  =======================================================
    
    .. autosummary::
       :toctree: generated/
    
       convert_temperature
       C2K
       K2C
       F2C
       C2F
       F2K
       K2F
    
    Energy
    ------
    
    ====================  =======================================================
    ``eV``                one electron volt in Joules
    ``electron_volt``     one electron volt in Joules
    ``calorie``           one calorie (thermochemical) in Joules
    ``calorie_th``        one calorie (thermochemical) in Joules
    ``calorie_IT``        one calorie (International Steam Table calorie, 1956) in Joules
    ``erg``               one erg in Joules
    ``Btu``               one British thermal unit (International Steam Table) in Joules
    ``Btu_IT``            one British thermal unit (International Steam Table) in Joules
    ``Btu_th``            one British thermal unit (thermochemical) in Joules
    ``ton_TNT``           one ton of TNT in Joules
    ====================  =======================================================
    
    Power
    -----
    
    ====================  =======================================================
    ``hp``                one horsepower in watts
    ``horsepower``        one horsepower in watts
    ====================  =======================================================
    
    Force
    -----
    
    ====================  =======================================================
    ``dyn``               one dyne in newtons
    ``dyne``              one dyne in newtons
    ``lbf``               one pound force in newtons
    ``pound_force``       one pound force in newtons
    ``kgf``               one kilogram force in newtons
    ``kilogram_force``    one kilogram force in newtons
    ====================  =======================================================
    
    Optics
    ------
    
    .. autosummary::
       :toctree: generated/
    
       lambda2nu
       nu2lambda
    
    References
    ==========
    
    .. [CODATA2014] CODATA Recommended Values of the Fundamental
       Physical Constants 2014.
    
       http://physics.nist.gov/cuu/Constants/index.html

PACKAGE CONTENTS
    codata
    constants
    setup

CLASSES
    builtins.DeprecationWarning(builtins.Warning)
        scipy.constants.codata.ConstantWarning
    
    class ConstantWarning(builtins.DeprecationWarning)
     |  Accessing a constant no longer in current CODATA data set
     |  
     |  Method resolution order:
     |      ConstantWarning
     |      builtins.DeprecationWarning
     |      builtins.Warning
     |      builtins.Exception
     |      builtins.BaseException
     |      builtins.object
     |  
     |  Data descriptors defined here:
     |  
     |  __weakref__
     |      list of weak references to the object (if defined)
     |  
     |  ----------------------------------------------------------------------
     |  Methods inherited from builtins.DeprecationWarning:
     |  
     |  __init__(self, /, *args, **kwargs)
     |      Initialize self.  See help(type(self)) for accurate signature.
     |  
     |  __new__(*args, **kwargs) from builtins.type
     |      Create and return a new object.  See help(type) for accurate signature.
     |  
     |  ----------------------------------------------------------------------
     |  Methods inherited from builtins.BaseException:
     |  
     |  __delattr__(self, name, /)
     |      Implement delattr(self, name).
     |  
     |  __getattribute__(self, name, /)
     |      Return getattr(self, name).
     |  
     |  __reduce__(...)
     |      helper for pickle
     |  
     |  __repr__(self, /)
     |      Return repr(self).
     |  
     |  __setattr__(self, name, value, /)
     |      Implement setattr(self, name, value).
     |  
     |  __setstate__(...)
     |  
     |  __str__(self, /)
     |      Return str(self).
     |  
     |  with_traceback(...)
     |      Exception.with_traceback(tb) --
     |      set self.__traceback__ to tb and return self.
     |  
     |  ----------------------------------------------------------------------
     |  Data descriptors inherited from builtins.BaseException:
     |  
     |  __cause__
     |      exception cause
     |  
     |  __context__
     |      exception context
     |  
     |  __dict__
     |  
     |  __suppress_context__
     |  
     |  __traceback__
     |  
     |  args

FUNCTIONS
    C2F(*args, **kwds)
        `C2F` is deprecated!
        scipy.constants.C2F is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Celsius to Fahrenheit
        
            Parameters
            ----------
            C : array_like
                Celsius temperature(s) to be converted.
        
            Returns
            -------
            F : float or array of floats
                Equivalent Fahrenheit temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``F = 1.8 * C + 32``.
        
            Examples
            --------
            >>> from scipy.constants import C2F
            >>> C2F(np.array([-40, 40.0]))
            array([ -40.,  104.])
    
    C2K(*args, **kwds)
        `C2K` is deprecated!
        scipy.constants.C2K is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Celsius to Kelvin
        
            Parameters
            ----------
            C : array_like
                Celsius temperature(s) to be converted.
        
            Returns
            -------
            K : float or array of floats
                Equivalent Kelvin temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``K = C + zero_Celsius`` where `zero_Celsius` = 273.15, i.e.,
            (the absolute value of) temperature "absolute zero" as measured in Celsius.
        
            Examples
            --------
            >>> from scipy.constants import C2K
            >>> C2K(np.array([-40, 40.0]))
            array([ 233.15,  313.15])
    
    F2C(*args, **kwds)
        `F2C` is deprecated!
        scipy.constants.F2C is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Fahrenheit to Celsius
        
            Parameters
            ----------
            F : array_like
                Fahrenheit temperature(s) to be converted.
        
            Returns
            -------
            C : float or array of floats
                Equivalent Celsius temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``C = (F - 32) / 1.8``.
        
            Examples
            --------
            >>> from scipy.constants import F2C
            >>> F2C(np.array([-40, 40.0]))
            array([-40.        ,   4.44444444])
    
    F2K(*args, **kwds)
        `F2K` is deprecated!
        scipy.constants.F2K is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Fahrenheit to Kelvin
        
            Parameters
            ----------
            F : array_like
                Fahrenheit temperature(s) to be converted.
        
            Returns
            -------
            K : float or array of floats
                Equivalent Kelvin temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``K = (F - 32)/1.8 + zero_Celsius`` where `zero_Celsius` =
            273.15, i.e., (the absolute value of) temperature "absolute zero" as
            measured in Celsius.
        
            Examples
            --------
            >>> from scipy.constants import F2K
            >>> F2K(np.array([-40, 104]))
            array([ 233.15,  313.15])
    
    K2C(*args, **kwds)
        `K2C` is deprecated!
        scipy.constants.K2C is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Kelvin to Celsius
        
            Parameters
            ----------
            K : array_like
                Kelvin temperature(s) to be converted.
        
            Returns
            -------
            C : float or array of floats
                Equivalent Celsius temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``C = K - zero_Celsius`` where `zero_Celsius` = 273.15, i.e.,
            (the absolute value of) temperature "absolute zero" as measured in Celsius.
        
            Examples
            --------
            >>> from scipy.constants import K2C
            >>> K2C(np.array([233.15, 313.15]))
            array([-40.,  40.])
    
    K2F(*args, **kwds)
        `K2F` is deprecated!
        scipy.constants.K2F is deprecated in scipy 0.18.0. Use scipy.constants.convert_temperature instead. Note that the new function has a different signature.
        
        
            Convert Kelvin to Fahrenheit
        
            Parameters
            ----------
            K : array_like
                Kelvin temperature(s) to be converted.
        
            Returns
            -------
            F : float or array of floats
                Equivalent Fahrenheit temperature(s).
        
            See also
            --------
            convert_temperature
        
            Notes
            -----
            Computes ``F = 1.8 * (K - zero_Celsius) + 32`` where `zero_Celsius` =
            273.15, i.e., (the absolute value of) temperature "absolute zero" as
            measured in Celsius.
        
            Examples
            --------
            >>> from scipy.constants import K2F
            >>> K2F(np.array([233.15,  313.15]))
            array([ -40.,  104.])
    
    convert_temperature(val, old_scale, new_scale)
        Convert from a temperature scale to another one among Celsius, Kelvin,
        Fahrenheit and Rankine scales.
        
        Parameters
        ----------
        val : array_like
            Value(s) of the temperature(s) to be converted expressed in the
            original scale.
        
        old_scale: str
            Specifies as a string the original scale from which the temperature
            value(s) will be converted. Supported scales are Celsius ('Celsius',
            'celsius', 'C' or 'c'), Kelvin ('Kelvin', 'kelvin', 'K', 'k'),
            Fahrenheit ('Fahrenheit', 'fahrenheit', 'F' or 'f') and Rankine
            ('Rankine', 'rankine', 'R', 'r').
        
        new_scale: str
            Specifies as a string the new scale to which the temperature
            value(s) will be converted. Supported scales are Celsius ('Celsius',
            'celsius', 'C' or 'c'), Kelvin ('Kelvin', 'kelvin', 'K', 'k'),
            Fahrenheit ('Fahrenheit', 'fahrenheit', 'F' or 'f') and Rankine
            ('Rankine', 'rankine', 'R', 'r').
        
        Returns
        -------
        res : float or array of floats
            Value(s) of the converted temperature(s) expressed in the new scale.
        
        Notes
        -----
        .. versionadded:: 0.18.0
        
        Examples
        --------
        >>> from scipy.constants import convert_temperature
        >>> convert_temperature(np.array([-40, 40.0]), 'Celsius', 'Kelvin')
        array([ 233.15,  313.15])
    
    find(sub=None, disp=False)
        Return list of physical_constant keys containing a given string.
        
        Parameters
        ----------
        sub : str, unicode
            Sub-string to search keys for.  By default, return all keys.
        disp : bool
            If True, print the keys that are found, and return None.
            Otherwise, return the list of keys without printing anything.
        
        Returns
        -------
        keys : list or None
            If `disp` is False, the list of keys is returned.
            Otherwise, None is returned.
        
        See Also
        --------
        codata : Contains the description of `physical_constants`, which, as a
            dictionary literal object, does not itself possess a docstring.
    
    lambda2nu(lambda_)
        Convert wavelength to optical frequency
        
        Parameters
        ----------
        lambda_ : array_like
            Wavelength(s) to be converted.
        
        Returns
        -------
        nu : float or array of floats
            Equivalent optical frequency.
        
        Notes
        -----
        Computes ``nu = c / lambda`` where c = 299792458.0, i.e., the
        (vacuum) speed of light in meters/second.
        
        Examples
        --------
        >>> from scipy.constants import lambda2nu, speed_of_light
        >>> lambda2nu(np.array((1, speed_of_light)))
        array([  2.99792458e+08,   1.00000000e+00])
    
    nu2lambda(nu)
        Convert optical frequency to wavelength.
        
        Parameters
        ----------
        nu : array_like
            Optical frequency to be converted.
        
        Returns
        -------
        lambda : float or array of floats
            Equivalent wavelength(s).
        
        Notes
        -----
        Computes ``lambda = c / nu`` where c = 299792458.0, i.e., the
        (vacuum) speed of light in meters/second.
        
        Examples
        --------
        >>> from scipy.constants import nu2lambda, speed_of_light
        >>> nu2lambda(np.array((1, speed_of_light)))
        array([  2.99792458e+08,   1.00000000e+00])
    
    precision(key)
        Relative precision in physical_constants indexed by key
        
        Parameters
        ----------
        key : Python string or unicode
            Key in dictionary `physical_constants`
        
        Returns
        -------
        prec : float
            Relative precision in `physical_constants` corresponding to `key`
        
        See Also
        --------
        codata : Contains the description of `physical_constants`, which, as a
            dictionary literal object, does not itself possess a docstring.
        
        Examples
        --------
        >>> from scipy import constants
        >>> constants.precision(u'proton mass')
        1.2555138746605121e-08
    
    unit(key)
        Unit in physical_constants indexed by key
        
        Parameters
        ----------
        key : Python string or unicode
            Key in dictionary `physical_constants`
        
        Returns
        -------
        unit : Python string
            Unit in `physical_constants` corresponding to `key`
        
        See Also
        --------
        codata : Contains the description of `physical_constants`, which, as a
            dictionary literal object, does not itself possess a docstring.
        
        Examples
        --------
        >>> from scipy import constants
        >>> constants.unit(u'proton mass')
        'kg'
    
    value(key)
        Value in physical_constants indexed by key
        
        Parameters
        ----------
        key : Python string or unicode
            Key in dictionary `physical_constants`
        
        Returns
        -------
        value : float
            Value in `physical_constants` corresponding to `key`
        
        See Also
        --------
        codata : Contains the description of `physical_constants`, which, as a
            dictionary literal object, does not itself possess a docstring.
        
        Examples
        --------
        >>> from scipy import constants
        >>> constants.value(u'elementary charge')
            1.6021766208e-19

DATA
    Avogadro = 6.022140857e+23
    Boltzmann = 1.38064852e-23
    Btu = 1055.05585262
    Btu_IT = 1055.05585262
    Btu_th = 1054.3502644888888
    G = 6.67408e-11
    Julian_year = 31557600.0
    N_A = 6.022140857e+23
    Planck = 6.62607004e-34
    R = 8.3144598
    Rydberg = 10973731.568508
    Stefan_Boltzmann = 5.670367e-08
    Wien = 0.0028977729
    __all__ = ['Avogadro', 'Boltzmann', 'Btu', 'Btu_IT', 'Btu_th', 'C2F', ...
    absolute_import = _Feature((2, 5, 0, 'alpha', 1), (3, 0, 0, 'alpha', 0...
    acre = 4046.8564223999992
    alpha = 0.0072973525664
    angstrom = 1e-10
    arcmin = 0.0002908882086657216
    arcminute = 0.0002908882086657216
    arcsec = 4.84813681109536e-06
    arcsecond = 4.84813681109536e-06
    astronomical_unit = 149597870691.0
    atm = 101325.0
    atmosphere = 101325.0
    atomic_mass = 1.66053904e-27
    atto = 1e-18
    au = 149597870691.0
    bar = 100000.0
    barrel = 0.15898729492799998
    bbl = 0.15898729492799998
    c = 299792458.0
    calorie = 4.184
    calorie_IT = 4.1868
    calorie_th = 4.184
    carat = 0.0002
    centi = 0.01
    day = 86400.0
    deci = 0.1
    degree = 0.017453292519943295
    degree_Fahrenheit = 0.5555555555555556
    deka = 10.0
    division = _Feature((2, 2, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0), 8192...
    dyn = 1e-05
    dyne = 1e-05
    e = 1.6021766208e-19
    eV = 1.6021766208e-19
    electron_mass = 9.10938356e-31
    electron_volt = 1.6021766208e-19
    elementary_charge = 1.6021766208e-19
    epsilon_0 = 8.854187817620389e-12
    erg = 1e-07
    exa = 1e+18
    exbi = 1152921504606846976
    femto = 1e-15
    fermi = 1e-15
    fine_structure = 0.0072973525664
    fluid_ounce = 2.9573529562499998e-05
    fluid_ounce_US = 2.9573529562499998e-05
    fluid_ounce_imp = 2.84130625e-05
    foot = 0.30479999999999996
    g = 9.80665
    gallon = 0.0037854117839999997
    gallon_US = 0.0037854117839999997
    gallon_imp = 0.00454609
    gas_constant = 8.3144598
    gibi = 1073741824
    giga = 1000000000.0
    golden = 1.618033988749895
    golden_ratio = 1.618033988749895
    grain = 6.479891e-05
    gram = 0.001
    gravitational_constant = 6.67408e-11
    h = 6.62607004e-34
    hbar = 1.0545718001391127e-34
    hectare = 10000.0
    hecto = 100.0
    horsepower = 745.6998715822701
    hour = 3600.0
    hp = 745.6998715822701
    inch = 0.0254
    k = 1.38064852e-23
    kgf = 9.80665
    kibi = 1024
    kilo = 1000.0
    kilogram_force = 9.80665
    kmh = 0.2777777777777778
    knot = 0.5144444444444445
    lb = 0.45359236999999997
    lbf = 4.4482216152605
    light_year = 9460730472580800.0
    liter = 0.001
    litre = 0.001
    long_ton = 1016.0469088
    m_e = 9.10938356e-31
    m_n = 1.674927471e-27
    m_p = 1.672621898e-27
    m_u = 1.66053904e-27
    mach = 340.5
    mebi = 1048576
    mega = 1000000.0
    metric_ton = 1000.0
    micro = 1e-06
    micron = 1e-06
    mil = 2.5399999999999997e-05
    mile = 1609.3439999999998
    milli = 0.001
    minute = 60.0
    mmHg = 133.32236842105263
    mph = 0.44703999999999994
    mu_0 = 1.2566370614359173e-06
    nano = 1e-09
    nautical_mile = 1852.0
    neutron_mass = 1.674927471e-27
    ounce = 0.028349523124999998
    oz = 0.028349523124999998
    parsec = 3.0856775813057292e+16
    pebi = 1125899906842624
    peta = 1000000000000000.0
    physical_constants = {'Angstrom star': (1.00001495e-10, 'm', 9e-17), '...
    pi = 3.141592653589793
    pico = 1e-12
    point = 0.00035277777777777776
    pound = 0.45359236999999997
    pound_force = 4.4482216152605
    print_function = _Feature((2, 6, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0)...
    proton_mass = 1.672621898e-27
    psi = 6894.757293168361
    pt = 0.00035277777777777776
    short_ton = 907.1847399999999
    sigma = 5.670367e-08
    speed_of_light = 299792458.0
    speed_of_sound = 340.5
    stone = 6.3502931799999995
    survey_foot = 0.3048006096012192
    survey_mile = 1609.3472186944373
    tebi = 1099511627776
    tera = 1000000000000.0
    ton_TNT = 4184000000.0
    torr = 133.32236842105263
    troy_ounce = 0.031103476799999998
    troy_pound = 0.37324172159999996
    u = 1.66053904e-27
    week = 604800.0
    yard = 0.9143999999999999
    year = 31536000.0
    yobi = 1208925819614629174706176
    yotta = 1e+24
    zebi = 1180591620717411303424
    zepto = 1e-21
    zero_Celsius = 273.15
    zetta = 1e+21

FILE
    //anaconda/envs/intro_sci_py3/lib/python3.6/site-packages/scipy/constants/__init__.py